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AVO versus AVA and effect of velocity gradient

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Proceedings Papers

Paper presented at the 1988 SEG Annual Meeting, October 30–November 3, 1988
Paper Number: SEG-1988-1221
... upstream oil & gas velocity variation ratio contrast calculation inversion poisson amplitude Effects of Velocity Variation on AVO and AVA Calculations S 20.8 Yu Xu and .I A. McDonald, Allied Geophysical Labs, University of Houston SUMMARY The effects of velocity variation on amplitude versus...
Proceedings Papers

Paper presented at the Offshore Technology Conference-Asia, March 25–28, 2014
Paper Number: OTC-24877-MS
... on the seismic response of the top reservoir and depend on the acoustic impedance contrast over the interface, and combined with the interference effect. Multiple AVA models have been studied and AVO attributes including intercept (I) and gradient (G) calculated to understand the rock property pattern...
Proceedings Papers

Paper presented at the 2006 SEG Annual Meeting, October 1–6, 2006
Paper Number: SEG-2006-0269
... Summary Fluid effects in carbonate rocks were successfully modeled to predict 4D related saturation changes and AVO/AVA (Amplitude Variations with Offset/Angle) seismic responses. The modeled predictions are in agreement with seismic observations in Abu Dhabi carbonate fields. The results...
Proceedings Papers

Paper presented at the 1994 SEG Annual Meeting, October 23–28, 1994
Paper Number: SEG-1994-0952
... (AVA) reflectivity curves indicate that process 1 is more accurate but computationally an order of magnitude more expensive than process 2. Maximum AVA relative errors for process 2 are 6% versus less than one percent for process 1. This demonstrates that even in this favorable case for process 2, AVO...
Proceedings Papers

Paper presented at the SPE/EAGE Reservoir Characterization and Simulation Conference, October 19–21, 2009
Paper Number: SPE-125383-MS
... of the reservoir layer and found to be AVO class-IV anomaly and were successful at discriminating brine from hydrocarbon but could not differentiate oil from gas. These encouraging results on synthetic data suggest that with good quality seismic data, it should be possible to see a difference in AVA response...
Proceedings Papers

Paper presented at the International Petroleum Technology Conference, December 7–9, 2009
Paper Number: IPTC-13136-MS
... and gradient result shows good agreement with the water saturation model. Figure (13) shows the encroachment of the waterfront especially on both flanks and along high permeability thief zones. The AVO results show water response where the model shows higher water saturations. AVA results show a positive...
Proceedings Papers

Paper presented at the 2005 SEG Annual Meeting, November 6–11, 2005
Paper Number: SEG-2005-0281
... contrast used in AVO calculations. These values were modeled from log data from a well in the South Timbalier South Addition area. AVO P1.5 SEG/Houston 2005 Annual Meeting 282 The effect of reflector dip on AVO analysis to the angle in the flat model (Figure 6). The shortened AVA curves are stretched...
Proceedings Papers

Paper presented at the 2011 SEG Annual Meeting, September 18–23, 2011
Paper Number: SEG-2011-0386
... of consolidation) versus porosity shows that the cemented Z Sandstone shear modulus exceeds that of the overlying shaly-sand interval and that of the underlying siltstone layer. Simultaneous AVA Inversion and Depth Conversion: The derived AVO depth trends have been constructed in the AI-Vp/Vs ratio domain to help...
Proceedings Papers

Paper presented at the 2018 SEG International Exposition and Annual Meeting, October 14–19, 2018
Paper Number: SEG-2018-2989842
... behavior, characterized by negative intercept and low gradient. The mapped AVO response matches the AVA model for both PSDM and PSTM seismic datasets. These evaluations are qualitative, since seismic amplitudes cannot be directly related to the AVA model s reflectivity. 10.1190/segam2018-2989842.1 Page 357...
Proceedings Papers

Paper presented at the 2007 SEG Annual Meeting, September 23–28, 2007
Paper Number: SEG-2007-0249
... on the AVA curvature can be erroneous. We then propose an alternative approach to use critical angle information extracted from AVA curves, and show that this leads to a significant improvement of the estimation of elastic parameters. Introduction Most AVO analysis and inversion techniques employed...
Proceedings Papers

Paper presented at the 1997 SEG Annual Meeting, November 2–7, 1997
Paper Number: SEG-1997-0206
..., amplitude variation created above the target zone. This allows to measure accurately the reflection coefficient at the target zone location free of propagation effects above it and in the seismic frequency bandwidth. Thanks to these characteristics, the AVO-AVA obtained from walkaway data is a robust bridge...
Proceedings Papers

Paper presented at the 2001 SEG Annual Meeting, September 9–14, 2001
Paper Number: SEG-2001-0118
...) should be used to further explore fracture related AVO/AVA effects. It is also clear that AVA analysis should precede even conventional AVO analysis to enable better understanding of the behaviour of the gradient and proper fluid replacement. Conclusion The result obtained in this study shows for all...
Proceedings Papers

Paper presented at the 2002 SEG Annual Meeting, October 6–11, 2002
Paper Number: SEG-2002-0304
... Summary The AVA-response of VTI-models for AVO-Classes 1 to 4 and two special cases is computed utilizing plane-wave reflection coefficients and the Weyl-integral. It is found that below 30º of angle, in most cases, the spherical VTIresponse departs more from an isotropic plane-wave comparison...
Proceedings Papers

Paper presented at the 2008 SEG Annual Meeting, November 9–14, 2008
Paper Number: SEG-2008-0242
... that the overburden is a constant-velocity layer, and exploit Dix equation to estimate the offset-to-angle conversion. Since the velocity distribution in the overburden is generally more complex, the effect on AVO and inversion of AVA data for the layerparameters can be significant. Usage of kinematically...
Proceedings Papers

Paper presented at the 2009 SEG Annual Meeting, October 25–30, 2009
Paper Number: SEG-2009-0256
..., 2008). Gather flattening is an essential step for anisotropic AVA estimation. As can be seen in Figure 1, multi azimuth data are not flat, due to the effects of anisotropy on the velocity/moveout. Without detailed high resolution gather flattening the AVO inversion procedure cannot deliver basic...
Proceedings Papers

Paper presented at the 2018 SEG International Exposition and Annual Meeting, October 14–19, 2018
Paper Number: SEG-2018-2997765
... Meeting, SEG, Expanded Abstracts, 342 346, httpsdoi.org/10.1190/segam2016- 13857890.1. Lynn, H. B., and B. Goodway, 2018, Effective porosity sensed changing by azimuth: A linear crossplot of azimuthal P-P (near angle amplitudes, AVO gradients): 88th Annual International Meeting, SEG, Expanded Abstracts...
Proceedings Papers

Paper presented at the 2013 SEG Annual Meeting, September 22–27, 2013
Paper Number: SEG-2013-0688
... for such characterization are AVO/AVA based inversions, which use the Zoeppritz equations and their different approximations (Zoeppritz, 1919; Shuey, 1985; Rutherford et al., 1989). AVO/AVA inversion gives good estimates of P- and S- wave velocities (VP and VS), and thus the VP-VS ratio (VP/VS) or the Poisson s ratio...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, September 15–20, 2019
Paper Number: SEG-2019-3214097
... on the crossplot are enclosed in a red polygon in (b) and back projected on the seismic section, they highlight the Duvernay zone, which is the source rock. (Data courtesy, TGS, Canada) Figure 7: (a) Crossplot of AVO intercept versus gradient over the zone of interest when (a) seismic velocity, (b) well-driven...
Proceedings Papers

Paper presented at the 2013 SEG Annual Meeting, September 22–27, 2013
Paper Number: SEG-2013-0381
... from reflection seismograms: Geophysics, 48, 1318 1337, httpdx.doi.org/10.1190/1.1441413. Pérez, D. O., and D. R. Velis, 2011, Sparse-spike AVO/AVA attributes from prestack data: 81st Annual International Meeting, SEG, Expanded Abstracts, 340 344. DOI httpdx.doi.org/10.1190/segam2013-0381.1© 2013 SEG...
Proceedings Papers

Paper presented at the 2015 SEG Annual Meeting, October 18–23, 2015
Paper Number: SEG-2015-5835519
... of zero phase seismic data and using a low cut filter (without wells), or by using colored inversion (with well). To illustrate AVO responses from the three attributes, we have considered a two-layer model, using the rock properties given by Blangy( 1994).The synthetic AVA data sampled at 2ms for two...

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